class MyInteger {
   public int val;
   MyInteger(int x) { val=x; }
}

class CallExample {
   public static void sqr(MyInteger a) {
      a.val=a.val*a.val;
      a=null;
   }

   public static void main(String[] args) {
      MyInteger c=new MyInteger(25);
      CallExample.sqr(c);
      System.out.println(c.val);
   }
}
